Publication Year 2016
Acceptance in OA@INAF 2020-07-03T08:19:30Z
Title VizieR Online Data Catalog: The SEGUE K giant survey. II. Distances of 6036 stars (Xue+, 2014)
Authors Xue, X. -X.; Ma, Z.; Rix, H. -W.; Morrison, H. L.; Harding, P.; et al.
DOI 10.26093/cds/vizier.17840170
Handle http://hdl.handle.net/20.500.12386/26301
Journal VizieR Online Data Catalog 01/06/2020 J/ApJ/784/170
Portal Simbad VizieR Aladin X-Match Other Help
J/ApJ/784/170 The SEGUE K giant survey. II. Distances of 6036 stars (Xue+, 2014)
The SEGUE K giant survey. II. A catalog of distance determinations for the SEGUE K giants in the galactic halo. Xue X.-X., Ma Z., Rix H.-W., Morrison H.L., Harding P., Beers T.C., Ivans I.I., Jacobson H.R., Johnson J., Lee Y.S., Lucatello S., Rockosi C.M., Sobeck J.S., Yanny B., Zhao G., Allende Prieto C.
ADC_Keywords: Milky Way ; Stars, halo ; Stars, K-type ; Stars, giant ; Abundances, [Fe/H] ; Radial velocities ; Stars, distances ; Photometry, SDSS Keywords: galaxies: individual (Milky Way) - Galaxy: halo - stars: distances - stars: individual (K giants)
Abstract: We present an online catalog of distance determinations for 6036 K giants, most of which are members of the Milky Way's stellar halo. Their medium-resolution spectra from the Sloan Digital Sky Survey/Sloan Extension for Galactic Understanding and Exploration are used to derive metallicities and rough gravity estimates, along with radial velocities. Distance moduli are derived from a comparison of each star's apparent magnitude with the absolute magnitude of empirically calibrated color-luminosity fiducials, at the observed (g-r)0 color and spectroscopic [Fe/H]. We employ a probabilistic approach that makes it straightforward to properly propagate the errors in metallicities, magnitudes, and colors into distance uncertainties. We also fold in prior information about the giant-branch luminosity function and the different metallicity distributions of the SEGUE K-giant targeting sub-categories. We show that the metallicity prior plays a small role in the distance estimates, but that neglecting the luminosity prior could lead to a systematic distance modulus bias of up to 0.25mag, compared to the case of using the luminosity prior. We find a median distance precision of 16%, with distance estimates most precise for the least metal-poor stars near the tip of the red giant branch. The precision and accuracy of our distance estimates are validated with observations of globular and open clusters. The stars in our catalog are up to 125kpc from the Galactic center, with 283 stars beyond 50kpc, forming the largest available spectroscopic sample of distant tracers in the Galactic halo.
Description: SDSS and its extensions use a dedicated 2.5m telescope to obtain ugriz imaging and resolution (defined as R=λ/Δλ)∼2000 spectra for 640 (SDSS spectrograph) or 1000 (BOSS spectrograph) objects over a 7deg2 field. Sloan Extension for Galactic Understanding and Exploration (SEGUE), one of the key projects executed during SDSS-II and SDSS-III, obtained some 360000 spectra of stars in the Galaxy, selected to explore the nature of stellar populations from 0.5kpc to 100kpc (Yanny et al. 2009, cat. J/AJ/137/4377; and C. M. Rockosi et al., in preparation). Data from SEGUE is a significant part of the ninth SDSS public data release (DR9; Ahn et al. 2012, cat. V/139).
The SEGUE project obtained spectra for a large number of different stellar types: 18 for SEGUE-1 (see Yanny et al. 2009, cat. J/AJ/137/4377, for details) and 11 for SEGUE-2 (C. M. Rockosi et al. in preparation). Three of these target types were specifically designed to detect K giants: these are designated "l-color K giants", "red K giants", and "proper-motion K giants." The K-giant targets from these three categories all have 0.5<(g-r)0<1.3, 0.5<(u-g)0<3.5, and proper motions smaller than 11mas/yr.
We present a catalog containing the distance moduli, observed information, and SEGUE Stellar Parameter Pipeline (SSPP) atmospheric parameters for 6036 SEGUE K giants (see Table4). For each object in the catalog, we also list some of the basic observables such as (R.A., decl.), extinction-corrected apparent magnitudes and dereddened colors, as well as the information obtained from the spectra--heliocentric radial velocities plus SSPP atmospheric parameters. In addition, we provide the Bayesian estimates of the distance moduli, distances to the Sun, Galactocentric distances, the absolute magnitudes and their uncertainties, along with the distance moduli at (5%, 16%, 50%, 84%, 95%) confidence of L(DM).
File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 19 1000 Interpolated fiducial table4.dat 158 6036 List of 6036 K giants selected from SDSS DR9
https://cdsarc.unistra.fr/viz-bin/ReadMe/J/ApJ/784/170?format=html&tex=true 1/3 01/06/2020 J/ApJ/784/170
See also: V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012) VII/202 : Globular Clusters in the Milky Way (Harris, 1997) J/ApJ/738/79 : SDSS-DR8 BHB stars in the Milky Way's halo (Xue+, 2011) J/ApJ/731/4 : Galactic halo as seen by the CFHTLS (Sesar+, 2011) J/AJ/141/90 : SEGUE stellar parameter pipeline. V. (Lee+, 2011) J/AJ/141/89 : SEGUE stellar parameter pipeline. IV. (Smolinski+, 2011) J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009) J/AJ/136/2070 : SEGUE stellar parameter pipeline. III. (Allende Prieto+, 2008) J/AJ/136/2050 : SEGUE stellar parameter pipeline. II. (Lee+, 2008) J/ApJ/684/1143 : BHB candidates in the Milky Way (Xue+, 2008) J/AJ/125/2502 : Spectral indices of Galactic halo (Morrison+, 2003) J/AJ/100/1191 : Giants DDO photometry (Morrison+, 1990)
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 5 F5.3 mag g-r [0.3/1.4] Extinction-corrected color index (g-r)0 7- 12 F6.3 mag rMag [-3.4/3] Absolute magnitude in r band (Mr) 14- 19 F6.3 [-] [Fe/H] [-2.4/0.4] Metallicity
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 8 F8.4 deg RAdeg Right Ascension in decimal degrees (J2000) 10- 17 F8.4 deg DEdeg Declination in decimal degrees (J2000) 19- 24 F6.3 mag rmag [13.8/19.6] Extinction-corrected r band magnitude (r0) 26- 30 F5.3 mag e_rmag [0.037/0.053] Error in rmag (Δr0) (1) 32- 36 F5.3 mag g-r [0.5/1.3] The (g-r) color index after extinction correction (g-r)0 38- 42 F5.3 mag e_g-r [0.018/0.044] Error in g-r (Δ(g-r)0) (1) 44- 49 F6.1 km/s HRV [-506.5/419.4] Heliocentic radial velocity 51- 54 F4.1 km/s e_HRV [0.5/15.1] Error in HRV 56- 59 I4 K Teff [4025/5691] Effective temperature (SSPP) (2) 61- 65 F5.2 [-] [Fe/H] [-3.6/0.32] Metallicity (SSPP) (2) 67- 70 F4.2 [-] e_[Fe/H] [0.1/0.23] Error in [Fe/H] (3) 72- 75 F4.2 [cm/s2] logg [0.18/3.5] Log of the surface gravity (SSPP) (2) 77- 81 F5.2 mag DMpeak [13.1/20.4] Distance modulus at peak of distance modulus likelihood (DMpeak) (4) 83- 87 F5.2 mag DM05 [12.2/20.3] Distance modulus at 5% confidence of distance modulus likelihood (DM5%) (4) 89- 93 F5.2 mag DM16 [12.6/20.3] Distance modulus at 16% confidence of distance modulus likelihood (DM16%) (4) 95- 99 F5.2 mag DM50 [13/20.4] Distance modulus at 50% confidence of distance modulus likelihood (DM50%) (4) 101-105 F5.2 mag DM84 [13.5/20.5] Distance modulus at 84% confidence of distance modulus likelihood (DM84%) (4) 107-111 F5.2 mag DM95 [13.7/20.6] Distance modulus at 95% confidence of distance modulus likelihood (DM95%) (4) 113-116 F4.2 mag eDM [0.05/0.76] Error in distance modulus estimate (ΔDM) (5) 118-122 F5.2 mag rMag [-3.2/1.2] Absolute magnitude in r band (Mr) (6) 124-127 F4.2 mag e_rMag [0.07/0.8] Error in rMag (ΔMr) 129-134 F6.2 kpc Dist [4.2/120.3] Distance to Sun (d) (6) 136-140 F5.2 kpc e_Dist [0.5/16.6] Error in Dist (Δd) 142-147 F6.2 kpc Rgc [4.79/125.1] Distance to Galactic center (rGC) (6) 149-153 F5.2 kpc e_Rgc [0/16.47] Error in Rgc (ΔrGC) 155-158 F4.2 --- pRGB [0.45/1] Chance of being clearly on the Red-Giant Branch (RGB), above the level of the Horizontal Branch (HB) (PaboveHB) (7)
Note (1): Corrected for measurement errors on the photometry and reddening (see Section 2). Note (2): SDSS DR9 delivers estimates of Teff, logg, [Fe/H], and [α/Fe] from an updated and improved version of the SEGUE Stellar Parameter Pipeline (SSPP; Lee et al. 2008AJ....136.2022L; Lee et al. 2008, cat. J/AJ/136/2050; Allende Prieto et al. 2008, cat. J/AJ/136/2070; Smolinski et al. 2011, cat. J/AJ/141/89; Lee et al. 2011, cat. J/AJ/141/90). The errors for Teff and log(g) are published in SDSS DR9, so we recommend readers to download them directly from CasJob. Note (3): Derived from Signal-to-Noise ratio (S/N), which is calibrated using https://cdsarc.unistra.fr/viz-bin/ReadMe/J/ApJ/784/170?format=html&tex=true 2/3 01/06/2020 J/ApJ/784/170 cluster data plus repeat observations, as described in detail in Morrison et al. (in preparation). Note (4): Distance moduli are derived from a comparison of each star's apparent magnitude with the absolute magnitude of empirically calibrated color-luminosity fiducials, at the observed (g-r)0 color and spectroscopic [Fe/H]. See Section 3 in the text for more details. DMpeak is the best estimate of the distance modulus for the K giant. Note (5): Calculated from (DM84%-DM16%)/2.
Note (6): Calculated from DMpeak, assuming R☉=8.0kpc ((DM+5)/5)) (i.e., rMag=rmag-DMpeak, d=10 . Note (7): See Section 3.4 in the text for further details.
History: From electronic version of the journal
References: Janesh et al., Paper III 2016ApJ...816...80J, cat. J/ApJ/816/80
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 03-Aug-2016
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